Round bales are made by introducing cut crop materials into a bale-making chamber of a baling machine and rotating the straw within the chamber using either belts or rollers. As the crop accumulates it is compressed to form a cylindrical bale (commonly referred to as a “round bale”). Various kinds of baling machines are known including both fixed and variable chamber designs, for example, as described in EP 1591004A. The present invention is applicable to all types of round baling machine.
Baling machines (or “balers”) generally include some means for applying a binding to the bale after it has been formed, to maintain the compression of the bale material and retain the shape and integrity of the bale after it has been discharged from the baler. Usually, the binding extends around and is attached to the cylindrical surface of the bale. Various binding materials have been used, including twine and plastic netting. Plastic film has also been used, but without great success, as this has some drawbacks. Generally, balers are designed to use just one of these binding materials.
After binding, the bale may optionally be wrapped in plastic film to protect the bale from degradation during storage and/or to encourage the formation of silage (fermented hay). The wrapping film can be applied around just the cylindrical surface of the bale (a partial wrap) or over the full surface of the bale, including the cylindrical surface and the circular end walls (a full wrap). The wrapping can be applied either by a dedicated wrapping machine or a combined baler/wrapper.
One disadvantage of using twine or netting as a binding material, particularly on bales that are subsequently fully wrapped, is that when the bale is being prepare for use, for example as fodder material, the farmer must remove the wrapping and the binding materials separately for recycling. This is difficult and increases the time and effort required to prepare the bale for use.
The problem can be avoided by using plastic film both as the binding material and as the wrapping material. The farmer can then remove both the binding and the wrapping in a single operation and there is no need to separate the materials for recycling. This saves considerable time and effort.
Further, if film is used as the binding material, less film material may subsequently be needed to complete the wrapping process as the bale is already partially wrapped.
A method of wrapping bales with protective film material is described in U.S. Pat. No. 5,079,898 (Indeco). In this method, the film material has a width less than the width of the bale and it is wound onto the cylindrical surface of the bale in a spiral pattern in order to cover the full width of the bale.
U.S. Pat. No. 6,971,220 (RPP) describes another method of wrapping a round bale, in which full width film material is used. The film is twisted into a rope prior to being introduced into the baling chamber.
Both of these methods have a number of problems, including at least some of the following.
In both RPP and Indeco, the leading end of the wrapping film is bundled together before it is fed into the bale chamber, and in RPP it is also twisted to form a rope. This improves handling and feeding of the film and prevents it blowing about in the wind. The trailing end of the film is also bundled to avoid leaving loose flaps of film on the outer surface of the bale. Bundling the film produces “tails” of film material at the start and end of each binding. These tails do not contribute effectively to the binding process and the film material consumed in forming these tails is therefore effectively wasted.
When using full width of film as in RPP, a considerable amount of film is wasted in forming the tails. When using reduced width film (Indeco), the amount of film wasted in forming the tails is reduced. However, in that case the wrapping process takes longer as more turns have to be applied to cover the entire width of the bale with a spiral wrapping pattern. A further problem with film wrapping generally is that the film material is considerably heavier per unit length than either twine or net binding material. The maximum weight of a roll of film material is limited by the fact that they have to be capable of being safely lifted and handled by an individual operator. Therefore, when using full width film as in RPP, the length of the film has to be quite short, with the result that it has to be replaced frequently. When using reduced width film as in Indeco, although the length of film on the roll can be increased, it is also consumed more quickly because more turns have to be applied to the surface of the bale. Therefore, the roll again has to be replaced frequently.
In both Indeco and RPP, the film is bundled using a pair of pivot arms that swing inwards and bring the edges of the film towards the centre, thus forming the tail close to the middle of the bale (between its two ends). The central region of the bale that lies beneath the tails therefore tends to be more compressed than the shoulders of the bale (where the cylindrical surface meets the circular end faces). This is less than ideal, since the shoulders of the bale are more vulnerable to damage during transportation and storage, and therefore require more protection. Further, neither of these prior art methods is capable of providing a binding that extends over the shoulders of the bale and onto the end faces to provide additional protection.
Also, bundling by pushing the edges of film towards the centre does not produce an even “rope” of film: the film is gathered more tightly at the edges than at the centre. The pivot arm mechanisms used in Indeco and RPP are also complex and expensive to manufacture. They also occupy a large space, which makes it difficult to add the mechanism onto an existing net binder machine.
It is an object of the present invention to provide a binding apparatus for a baling machine, and a method of binding a bale, that mitigates one or more of the aforesaid disadvantages.